The 25 cities with the most economic power on earth

There's fierce competition among the world's most powerful and influential cities, and there are a lot of questions: Are the megacities cropping up in the developing world displacing the western world's hubs? Does London or New York come out on top?

They've based it on four major factors: Overall economic clout, equity and quality of life, financial power and global competitiveness. Their estimates for these are drawn from a bundle of different sources.

There are some surprising cities pretty high up on in the ranks, and you can check where they all sat three years ago when the list was last made. Some have surged up the ranks and some have dropped back considerably.